1. Field of the Invention
The present invention generally relates to a driving technique. More specifically, the present invention relates to a method of driving a plasma display, in which the plasma screen is divided into two or more regions and the scan operation and the sustain operation are coincident in timing, thereby increasing the working period of the sustain operation and improving the brightness level of the plasma display.
2. Description of the Related Art
In the current driving technique for plasma displays, the whole screen of a plasma display is driven by three kinds of operations, including the reset operation, the scan operation and the sustain operation. In detail, a frame-display operation in the plasma display includes several sub-frame operations. The number of the sub-frames in one frame depends on the bit-depth of gray scales nor example, one frame in a plasma display with 256 gray scales, which means a bit-depth of 8 bits, includes eight sub-frames. Each sub-frame operation involves one reset operation, one scan operation and one sustain operation.
Using the conventional driving technique, the scan operation usually wastes a lot of operating time in the predefined frame period. For a plasma display with 256 gray scales and a resolution of 800xc3x97600, suppose that each of the reset operation requires 150 xcexcs and the time for scanning a scanning line is about 3 xcexcs. Then the total time for the reset operations and the scan operations in one frame-display operation is about (150+3xc3x97600)xc3x978=15.6 ms, which exceeds 90% of the frame period (16.7 ms) specified in NTSC standard. Therefore, the remaining time for the sustain operation is inadequate to produce sufficient brightness on the plasma display. In addition, such driving technique cannot be applied to plasma displays with higher resolutions, such as 1280xc3x971024.
FIG. 1 (Prior Art) is a top view of a three-electrode surface discharge plasma display with a resolution of 800xc3x97600. Numeral 1 represents a plasma display panel. Numeral 2 represents X-electrodes. Numeral 3 (including 31xcx9c3600) represents Y-electrodes. Numeral 4 (including 41xcx9c4800) represents data electrodes. Numeral 5 represents picture pixels, which are defined by X-electrodes 2, Y-electrodes 3 and data electrodes 4. It is noted that the total number of the picture pixels is 800xc3x97600. Numeral 6 represents ribs that are used to separate picture pixels 5. L1xcx9cL600 represent display scanning lines.
FIG. 2 (Prior Art) is a schematic cross-sectional view of picture pixel 5 in the plasma display. In FIG. 2, numerals 8 and 9 represent a rear glass substrate and a front glass substrate, respectively. Numeral 10 represents an insulation layer that covers X-electrode 2 and Y-electrodes 3. Numeral 11 represents a passivation layer, for example, made of MgO. Numeral 12 represents a fluorescent layer. Numeral 13 represents discharge space.
FIG. 3 (Prior Art) is a circuit diagram showing the plasma screen and its peripheral circuitry. Numeral 14 represents an X driver circuit for providing writing pulses and sustaining discharge pulses to X-electrode 2. Numeral 15 represents Y driver ICs for providing addressing pulses to Y-electrodes 31xcx9c3600. Numeral 16 represents an Y driver circuit for providing addressing pulses to Y driver ICs 15. Numeral 17 represents data driver ICs for providing data pulses to data electrodes 41xcx9c4800. Numeral 18 represents a control circuit for controlling X driver circuit 14, Y driver ICs 15, Y driver circuit 16 and data driver ICs 17.
FIG. 4 (Prior Art) is a schematic diagram for illustrating a full frame-display operation using the conventional driving technique. As shown in FIG. 4, one frame-display operation consists of eight sub-frame operations SF1xcx9cSF8. Each sub-frame operation includes a reset step, a scan step and a sustain step. The working periods of the reset operations or the scan operations in these sub-frame operations are the same. In other words, Tw1=Tw2=. . . =Tw8 and Ta1=Ta2=. . . =Ta8. The working periods for the sustain operations in one frame-display operation are assigned at a fixed ratio, thereby exhibiting various gray scales. In the case of 256 gray scales, the ratio of the working periods of the eight sustain steps can be assigned to 1:2:4:8:16:32:64:128.
In addition, the working period for the scan operation is proportional to the number of the scanning lines. Therefore, when the resolution increases, the ratio of the scan operation occupied in the whole frame-display operation also increases. This may cause two problems. First, since the usable time for each frame-display operation is fixed, extending the period of the scan operation may result in the shortening of the sustain operation. However, the brightness level of the plasma display depends on the period of the sustain operation. Therefore, the plasma display using the conventional driving technique suffers the drawback of insufficient brightness. Second, since the period of the scan operation is restricted by the usable time dedicated to the frame-display operation, this conventional driving technique cannot be directly applied in the plasma display with higher resolutions.
Therefore, an object of the present invention is to provide a method of driving a plasma display for increasing the period of the sustain operations, thereby improving the brightness level and the resolution limitation of the plasma display.
The present invention achieves the above-indicated objects by providing a method of driving a plasma display, in which a frame is displayed by sequentially performing a reset operation, a scanning operation and a sustain operation. First, the screen of the plasma display is divided into a plurality of non-overlapped sub-regions. These sub-regions can be individually driven for displaying. Then these sub-regions are sequentially driven by the reset operation, the scanning operation and the sustain operation. During the driving process, the sustain operation on one of the sub-regions is synchronized with the scan operation of another one of the sub-regions that is subsequently processed. In addition, the reset operation on one of the sub-regions does not overlap the scan operations and the sustain operations on others sub-regions, which means that any operations on these sub-regions cannot be performed during the process of the reset operation.
For example, the screen of the plasma display can be divided into a first sub-region and a second sub-region. When a reset operation is performed on the first (second) sub-region of the screen of the plasma display, the controller must halt driving the second (first) sub-region for preventing signal interference between these sub-regions. When a scan operation is performed on the first (second) sub-region, the controller can perform the sustain operation on the second (first) sub-region. Therefore, the working period of the sustain operation does not need to occupy extra time and can be maximally extended to be the working period of the scan operation, thereby improving the brightness level of the plasma display and overcoming the resolution limitation.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with respect to the accompanying drawings.